The present invention relates to a mechanism for allowing the transmission of electrical signals between a rotating member and an adjacent stationary member. More specifically, the invention relates to a reel mechanism for a signal transmission cord attaching a rotary member such as a steering wheel column to an adjacent member such as a portion of an automobile frame.
The prior art in the field, see for example FIGS. 3 and 4, includes a reel mechanism having an inner cylinder 4 and an outer cylinder 7 which are both coaxially mounted on a rotating member. A signal transmission cord 6 is wrapped circumferentially around the inner cylinder 4 forming a number of layers of cord 6. The cord 6 is attached at one end to the inner cylinder 4 by a fastener 5 and is attached at the other end to a remote member. The outer cylinder 7 is hollow and covers the cord wrapped around the inner cylinder. When the rotary member is rotated, cord is circumferentially wound or unwound from the inner cylinder.
The problem with the prior art device described above is that when the cord is wound and unwound numerous times, the cord has a tendency to buckle 8 near its connection point with the inner cylinder 4. Buckling of the cord near the attachment point causes the cord to weaken and break, thus significantly shortening the useful life of the cord reel.
A currently practiced design for preventing buckling of the cord near its attachment point is a buckling prevention member 9 secured to the inner cylinder 4 to guide the cord 6 to assure a smooth form near the cylinder 4. The cord extends alongside the member 9 which is curved to a shape similar to that of the inner cylinder 4.
However, the above-mentioned prior art device does not solve the problem adequately, and is also more expensive to manufacture. Considerable time and effort are consumed attaching the buckling prevention member to the inner cylinder and arranging the cord to extend properly along the member. Also, the additional piece is expensive to manufacture and even when properly attached does not effectively prevent the cord from buckling.
The present invention addresses the problems mentioned above. It is an object of the invention to provide a cord reel device which prevents the cord from buckling and which does not require the time, effort and expense to assemble many parts, thus providing an innexpensive and durable cord reel mechanism.